The present invention relates generally to an internal combustion engines, and more particularly to a valve-controlled system for generating a sufficient back pressure within an engine exhaust system to force an engine exhaust gas into an engine intake manifold during an exhaust gas recirculation (EGR) mode.
During the exhaust gas recirculation (EGR) mode of an internal combustion engine, a flow path must be established from the engine exhaust gas manifold through the engine exhaust gas recirculation (EGR) cooler and into the engine intake manifold after having passed through the exhaust gas recirculation (EGR) cooler. The pressure generated within an exhaust gas recirculation (EGR) system must be high enough to force a desired portion of the exhaust gas into the intake manifold so as not to be exhausted or routed through the turbine side of the engine turbocompressor. Prior art systems have utilized pumps, venturis, and/or similar devices to create sufficient high pressure, back pressure, and/or differential pressure drops within the respective systems, however, such devices or components have considerable expenditures.
A need therefore exists in the art for a relatively simple and low-cost control mechanism which can be readily and easily used with the exhaust gas recirculation (EGR) system of an internal combustion engine. The exhaust gas recirculation (EGR) system must have sufficiently high pressure or back pressure to force the engine exhaust gas into the engine intake manifold properly enabling or facilitating the exhaust gas recirculation (EGR) mode for the engine.
In one aspect of the invention, an exhaust gas recirculation (EGR) system is adapted for use with an internal combustion engine. The exhaust gas recirculation (EGR) system has an exhaust gas recirculation (EGR) conduit interposed an exhaust manifold structure of the engine and an atmospheric exhaust structure. And, a valve mechanism is disposed within the exhaust gas recirculation (EGR) conduit and movable between a fully closed position at which an entrance to the exhaust gas recirculation (EGR) conduit is blocked and all exhaust gas from the engine passes to atmospheric exhaust through the atmospheric exhaust structure, and a fully opened position at which the valve mechanism opens the entrance to the exhaust gas recirculation (EGR) conduit and partially occludes the atmospheric exhaust structure such that a sufficiently large back pressure is developed with respect to the atmospheric exhaust structure such that exhaust gases are forced through the exhaust gas recirculation (EGR) conduit.
In another aspect of the invention, a method provides exhaust gas recirculation to an internal combustion engine. The internal combustion engine has a plurality of cylinders, an atmospheric exhaust structure, an intake manifold, a first exhaust manifold being in fluid communication with a first portion of the plurality of cylinders, and a second exhaust manifold being in fluid communication with a second portion of the plurality of cylinders. The method has the following steps. Providing a conduit interposed one of the first portion of the plurality of cylinders and the second portion of the plurality of cylinders and the intake manifold. Providing a valve mechanism in the conduit. Moving the valve mechanism into a closed position during an operating mode of the internal combustion engine so that an exhaust gas from the plurality of cylinders is directed to the atmospheric exhaust structure. Moving the valve mechanism into an open position during an operating mode of the internal combustion engine so that the exhaust gas from one of the first portion and the second portion creating a large back pressure with respect to an exhaust gas within the atmospheric exhaust structure and being directed to the intake manifold. And, moving the valve mechanism into a position intermediate the open position and the closed position during an operating mode of the internal combustion engine so that a predetermined quantity of the exhaust gas from one of the first portion and the second portion creating a large back pressure with respect to an exhaust gas within the atmospheric exhaust structure being directed to the intake manifold.